1. Field of the Invention
This invention relates to an electric power supply device and more particularly, to a rechargeable electric power supply device which is adapted for use in solar modules, such as solar cars, solar boats, solar scooters and the like, along with known lead and like batteries. Because the rechargeable device exhibits good constant current charge and constant voltage charge characteristics, the functions of the solar modules are fully complemented with increasing charge efficiency and utilization efficiency being attained. The rechargeable device has such a great electric capacitance that it is rechargeable like capacitors from the standpoint of its function.
2. Description of the Prior Art
With rechargeable batteries which are employed in known solar modules as having, for example, a rating of DC 12V, the electric generation from the solar module is not enough to charge the battery under rainy or cloudy weather conditions. If the battery is charged at a potential of DC 12V or below, the battery is not charged at all irrespective of how to generate electricity or how to charge. Thus, the generated electricity is discharged only in vain.
Various types of DC charge devices have been heretofore proposed. However, all the devices have complicated structures. Nevertheless, great constant current charge characteristic and constant voltage charge characteristics are not obtained with a low charge efficiency. More particularly, substantially all electric charges pass at one time and disappear at the time of primary discharge, and a charge time is long. When charge and discharge operations are repeated, the solar modules may often suffer damages, resulting in the shortage of life of the module. Thus, the known charge devices are disadvantageous in the complicated structure and also in economy.